Growing from Seed: Part 2

Sow slow-germinating seeds now

By Dr. Francis Gouin

As you know from last week’s calendar of when to sow what, now into early March is the time to sow seeds of onions and shallots, begonias and coleus, petunias and impatients. These very fine-seeded species require special treatment. Here’s what to do.
Buy a commercial seed starter that’s a sterile fine mixture of peat moss, pine bark and fine vermiculite amended with limestone to adjust the pH to near 6.5.
Sow onions and shallots in four-inch pots with drainage holes. The seedlings will grow in these containers until you transplant them to the garden. Fill the pot to the top with seed starter; scrape away the excess. Bounce the bottom of the pot several times on your work surface to eliminate air pockets. Smooth the surface of the growing medium. Now uniformly spread 30 to 40 seeds over the surface. Watering the seeds will cover them with medium as it causes additional settling.
The seeds will germinate best at temperatures between 75 to 80 degrees. The top of the refrigerator supplies the heat to make an ideal germinating table. As soon as seedlings appear, move the pots to a window facing south for maximum sunlight — or into a greenhouse. Irrigate as needed. Fertilize after seedlings have grown two to three inches tall. Use either fish emulsion or a diluted commercial water-soluble fertilizer. For starting seeds of begonia, coleus, impatients, petunia and so on, salad trays — the plastic kind you fill at salad bars — are ideal. Using an ice pick or a pointed knife, punch holes uniformly across the bottom, spacing the holes one inch apart. Punch from the inside out. Next add at least one to two inches of seed-starting mix. Using plant labels, divide the surface area of the starter mix so that each species gets approximately two by two inches. Scatter the seeds uniformly over their area, label each species and sprinkle with water until the excess drips out the container’s bottom. Snap the clear cover closed and place the container on top of the refrigerator.
As soon as the seeds start to germinate, move the container to a window facing south or to a greenhouse. To prevent the build-up of heat within the salad bar container, lay a pencil or wooden dowel half-way between the hinge and the front edge of the container, across the length of the container and wrap with a rubber band to keep the cover partially closed. The seedlings will be ready to transplant into larger pots as soon as they can be lifted.